Systems and methods for fabricating microstructures

Abstract

Methods for forming microstructures in photocurable material are described. At least one image of light or radiation for curing the photocurable material is applied in a pattern corresponding to the image. The image is formed by near-field diffraction of the light or radiation and comprises areas of higher intensity adjacent to areas of lower intensity.

What is claimed is: 
     
         1 . A method for forming microstructures, comprising:
 applying, to a photocurable material, at least one image of light or radiation for curing the photocurable material in a pattern corresponding to the image, wherein each image is formed by near-field diffraction of the light or radiation through at least one photomask and comprises areas of higher intensity adjacent to areas of lower intensity; and   maintaining or substantially maintaining each image during the applying for a duration sufficient to effect curing of the photocurable material, the curing forming microstructures within the photocurable material;   wherein the at least one image of light or radiation comprises a first image and a second image, and the first and second images are interleaved in which areas of higher intensity of the first image are applied in locations of lower intensity for the second image;   and wherein an operating distance between the at least one photomask and the photocurable material remains substantially constant during the applying step.   
     
     
         2 . The method of  claim 1 , wherein the first image and the second image are each substantially a Talbot image formed at an integer multiple of a quarter of a Talbot length. 
     
     
         3 . The method of  claim 1 , wherein the first image and the second image are each substantially a Talbot image formed at a half or an integer multiple of a half of a Talbot length. 
     
     
         4 . The method of  claim 1 , wherein the first image and the second image are each substantially a Talbot image formed at a full or an integer multiple of a full Talbot length. 
     
     
         5 . The method of  claim 1 , wherein the at least one photomask comprises a dynamic photomask and the first image is applied by a first configuration of dynamic photomask and the second image is applied by a second configuration of the dynamic photomask. 
     
     
         6 . The method of  claim 1 , wherein the light or radiation is non-monochromatic light or multimodal light. 
     
     
         7 . The method of  claim 1 , wherein the at least one photomask comprises a first diffraction grating and a second diffraction grating and wherein said applying at least one image of light or radiation for curing the photocurable material comprises applying the first image by the first diffraction grating and the second image by the second diffraction grating that is offset from the first diffraction grating. 
     
     
         8 . The method of  claim 7 , wherein the first diffraction grating and the second diffraction grating both comprise slits with a first separation distance and wherein the offset is substantially equal to half the first separation distance. 
     
     
         9 . The method of  claim 1 , wherein the method comprises causing the first image and the second image to traverse the photocurable material while maintaining areas of higher intensity of the first image interleaved with areas of higher intensity of the second image. 
     
     
         10 . The method of  claim 1 , wherein each said image has a periodic or quasi-periodic pattern across a first dimension. 
     
     
         11 . The method of  claim 1 , wherein at least the first image has a periodic or quasi-periodic pattern in two dimensions. 
     
     
         12 . The method of  claim 1 , wherein applying the least one image of light or radiation is through a transparent or semi-transparent substrate of the photocurable material. 
     
     
         13 . The method of  claim 12 , wherein the transparent or semi-transparent substrate is from a roll and the method comprises transferring the substrate from the roll to another roll and applying the at least one image of light or radiation at an intermediate point between the two rolls. 
     
     
         14 . The method of  claim 1 , wherein the light is sourced from one or more lasers. 
     
     
         15 . The method of  claim 1 , wherein the microstructures have a height between 0.10 and 250 microns (inclusive). 
     
     
         16 . The method of  claim 1 , wherein the microstructures have a height between 25 and 250 microns (inclusive). 
     
     
         17 . The method of  claim 1 , wherein the microstructures have a height between 0.1 and 5 microns (inclusive). 
     
     
         18 . The method of  claim 1 , comprising leaving the microstructures within the photocurable material. 
     
     
         19 . The method of  claim 1 , comprising at least partially removing photocurable material to expose the microstructures. 
     
     
         20 . The method of  claim 1 , wherein applying the at least one image of light or radiation is by a portable applicator comprising at least one light source for providing the applied light and an optical system for receiving light from the at least one light source and generating the at least one image.